This seminars deals with the techniques of characterization of cracks and micro cracks in concrete and mortars. It gives an overall view of the methods of observation in relation with image analysis. Image analysis is a useful tool to extract crack patterns from samples of concrete, since many fields are necessary to be studied at high magnifications. An analysis of the procedures and of the provided 2-D data is proposed. The parameters of damage characterization are listed and discussed. Improvements and ways of research are suggested, mainly to extend 2-D results to 3-D space by means of crack-pattern modeling.